As will be understood by persons of ordinary skill in the art, single phase induction motors may be of many different types. Thus, there are resistance start, reactor start, capacitor start, permanent split capacitor, and capacitor start-capacitor run motors to name but a few. These different types of motors are characterized by different speed-torque characteristics, and of course are capable of being designed to have different theoretical maximum efficiencies. For many applications, and especially those where high starting torque is required, it is necessary for part of the windings in the motor to be designed and arranged to be an auxiliary or starting winding which is energized during initial excitation of the motor but which is de-energized as the motor comes up to a predetermined speed.
One particular reference work that describes motor characteristics and gives specific application information regarding different motors is the C. G. Veinott book entitled, "Fractional And Subfractional Horsepower Electric Motors", published by the McGraw-Hill Book Company. For more information on this subject, the reader is directed, for example, to the third edition of the Veinott book which was copyrighted in 1970 by McGraw-Hill.
In many applications, it is known to use a centrifugally or otherwise actuated switch assembly for de-energizing the auxiliary or starting winding as the motor comes up to speed, and it is desirable to optimize such assemblies in terms of material content, assembly cost, and reliability. Some problems with some switch assembly designs that have been used heretofore, are believed to have been associated with a condition wherein the switch contacts have been "open" to their environment and subject to damage, or to lodging of foreign material on or about such contacts. Another continuing concern for all types of motor circuit controlling switches is the question of accessibility or serviceability of such switches as well as the cost associated with replacing such switches. It thus also would be desirable to provide a new and improved switch of non-complex design which is reliable in operation.
In switches of the type here contemplated, the long term maintenance of desired dimensional relationships of different switch parts and components is important, in order that desired switch action characteristics result, such as: good contact wiping action; contact self-cleaning action; controlled and limited lost motion relative travel of two or more switch parts; reliable switch action notwithstanding dimensional tolerance accummulations; collinear relationship of contacts and actuator line of travel; weld breaking action; and near-parallel relationship of two contacts.